Seal assembly for hydraulic pump output shaft

ABSTRACT

A seal assembly for a hydraulic pump is provided. The assembly includes a spacer ring, a rotor having a first side and a second side, the first side engaging the spacer ring, and a spring-loaded face seal having a face in contact with the rotor second side, where the face seal is configured to supply a force against the rotor sufficient to cause the face seal face to sealingly engage the rotor second side.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/656,286, filed Feb. 24, 2005.

TECHNICAL FIELD

The present invention relates to a hydraulic pump and, moreparticularly, to a seal assembly for use on an output shaft of ahydraulic pump.

BACKGROUND

A gas turbine engine may include a hydraulic pump for powering certainengine components. In one example, a hydraulic pump may be used tohydraulically power actuators that control an afterburner exhaustnozzle. The hydraulic pump includes a shaft that extends to an aircraftengine gearbox and that extends the length of the pump to communicatewith a plurality of hydraulic pump components, such as pistons, gears,or vanes. A portion of the shaft, the hydraulic pump components, andhydraulic fluid are disposed within a housing.

When the aircraft engine gearbox drives the shaft, the shaft rotateswithin the hydraulic pump to thereby provide power to the pistons,gears, or vanes to force hydraulic fluid through the pump. As a result,power is provided to the aforementioned actuators.

To prevent leakage of the hydraulic fluid from the area along the shaftwhere the shaft extends through the housing, a magnetic seal hastypically been used. In this regard, one section of the magnetic seal ismounted to a stator of the pump, which is typically coupled to thehousing, and another section of the magnetic seal is mounted to a rotorof the pump, which is typically coupled to the shaft. The two sectionsof the magnetic seal attract one another to provide a leak-tight sealbetween the shaft and the housing.

In some cases, however, the magnetic seal may not effectively seal thehydraulic pump. For example, if the stator and rotor experience arelatively large amount of axial travel therebetween, the magnetic sealmay separate which may result in loss of oil. Additionally, if metalchips are inadvertently generated inside the pump, the metal chips mayinterfere with the magnetic seal and separation may occur.

Accordingly, there is a need for seal assembly that is effective evenwhen a hydraulic pump stator and a rotor experience axial traveltherebetween. In addition, there is a need for seal assembly thatcontinues to be operational, in the event metal chips are generatedinside the pump. Furthermore, other desirable features andcharacteristics of the present invention will become apparent from thesubsequent detailed description and the appended claims, taken inconjunction with the accompanying drawings and the foregoing technicalfield and background.

BRIEF SUMMARY

The present invention provides a seal assembly for a hydraulic pump. Theassembly includes a spacer ring, a rotor having a first side and asecond side, the first side engaging the spacer ring, and aspring-loaded face seal having a face in contact with the rotor secondside, where the face seal is configured to supply a force against therotor sufficient to cause the face seal face to sealingly engage therotor second side.

In another embodiment, and by way of example only, a hydraulic pump isprovided that includes a housing, a shaft rotationally mounted at leastpartially within the housing, a spacer ring mounted to the shaft, arotor mounted to the shaft and having a first side and a second side,where the rotor first side engages the spacer ring, and a spring-loadedface seal coupled to the housing and having a face in contact with therotor second side, the face seal configured to supply a force againstthe rotor sufficient to cause the face seal face to sealingly engage therotor second side.

In still another embodiment, a seal-assembly for a hydraulic pumpincludes a spacer ring, a rotor having a first side and a second side,the first side engaging the spacer ring, a stator having a face incontact with the rotor second side, a seal case within which the statoris disposed, and a spring disposed within the seal case, the springconfigured to supply a force against the rotor that is sufficient tocause the stator face to sealingly engage the rotor second side.

Other independent features and advantages of the preferred seal assemblywill become apparent from the following detailed description, taken inconjunction with the accompanying drawings which illustrate, by way ofexample, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a conventional hydraulic pump;

FIG. 2 is an exemplary seal assembly for use in the conventionalhydraulic pump of FIG. 1;

FIG. 3 is an isometric view of a portion of the exemplary seal assemblydepicted in FIG. 2; and

FIG. 4 is a cross sectional view of a portion of another exemplaryembodiment of the seal assembly.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Before proceeding with the detailed description, it should beappreciated that the present invention is not limited to use inconjunction with a specific type of rotating machine. Thus, although thepresent invention is, for convenience of explanation, depicted anddescribed as being implemented in a turbine starter, it should beappreciated that it can be implemented in numerous other machinesincluding, but not limited to, a gas turbine engine, a hydraulic pump, awater pump, or various other chemical and industrial pumps.

Turning now to the description, a cross sectional view of a conventionalhydraulic pump 100 is provided in FIG. 1. The hydraulic pump 100 may beany one of numerous types of pumps capable of producing hydraulic power.For example, the hydraulic pump 100 may be a centrifugal pump, apositive displacement pump, a reciprocating positive pump, or any othersuitable type of pump. In any case, the pump 100 includes at least ahousing 102, a shaft 104, and a seal assembly 200. The housing 102contains a portion of the shaft 104 and the seal assembly 200 andincludes hydraulic fluid that is pumped therethrough. The housing 102may be a single piece, or alternatively, and as shown in FIG. 1, thehousing 102 may be an assembly of multiple pieces. In an exemplaryembodiment in which the housing 102 is multiple pieces, the housing 102may include an outer housing 110 and a cover plate 112 that are coupledto one another. The cover plate 112 includes an opening 114 formedtherein.

The shaft 104 is rotationally mounted within the housing 102 and extendsthrough the cover plate opening 114. The shaft 104 has a pump section118 and a gearbox section 120. The pump section 118 extends axiallythrough the housing 102 and is configured to couple to various hydraulicpump components (not shown), such as pistons, gears, and/or vanes. Itwill be appreciated that the particular hydraulic pump componentsincluded in the housing 102 depend on the hydraulic pump type, forexample, a centrifugal pump, a positive displacement pump, areciprocating positive pump, or any other type of pump. The gearboxsection 120 extends outside of the housing 102 and has an end 122configured to couple to a gearbox (not shown).

To minimize friction that may occur when the shaft 104 rotates, abearing assembly 124 is mounted thereto. The bearing assembly 124includes an inner race 126, an outer race 128, and balls 130. The innerrace 126 contacts the shaft 104 and rotates therewith. The outer race128 positions the balls 130 against the inner race 126 and is coupled toa portion of the housing 102, such as, for example, to the cover plate112.

The seal assembly 200 seals the hydraulic fluid within the housing 102and prevents the hydraulic fluid from leaking between the shaft 104 andthe cover plate 112. FIG. 2 provides a close up view of the sealassembly 200. The seal assembly 200 includes a spacer ring 202 and aface seal assembly 204. The spacer ring 202 is disposed between theshaft 104 and inner race 126 and is mounted to the shaft 104 to therebyrotate therewith. The spacer ring 202 has a retaining end 206 and amating end 208. The retaining end 206 abuts a portion of the shaft 104that extends radially outwardly to prevent axial movement of the spacerring 202 along the shaft 104. The mating end 208 preferably includes twogrooves 210, 212 formed thereon that are configured to mate with aportion of the face seal assembly 204, which will be described in moredetail below. Although two grooves 210, 212 are depicted, it will beappreciated that fewer or more than two grooves may alternatively beemployed.

With reference now to both FIGS. 2 and 3, the face seal assembly 204includes a rotor 214, a seal case 216, and stator 218. The rotor 214 isdisposed adjacent to and in contact with the spacer ring mating end 208and is mounted to the shaft 104. The rotor 214 includes a mating face220 and a sealing face 222. The mating face 220 preferably has twoaxially extending flanges 224, 226 formed thereon that correspond andengage with the two grooves 210, 212, respectively, in the spacer ring202. Just as with the grooves 210, 212, fewer or more than two flanges224, 226 may be alternatively employed. Moreover, although the grooves210, 212 are shown as being formed on the spacer ring 202 and theflanges 224, 226 are depicted as being formed on the rotor 214, it willbe appreciated that the grooves 210, 212 may alternatively be formed onthe rotor 214 and the flanges 224, 226 may be alternatively formed onthe spacer ring 202, as shown in FIG. 4.

Returning to FIG. 2, the rotor 214 may have a channel 228 formed in itsinner peripheral surface 230 within which an O-ring 232 is disposed. TheO-ring 232 provides a leak-tight seal between the rotor 214 and theshaft 104.

The seal case 216 is mounted to the housing 102, for example, the coverplate 112, and surrounds the shaft 104. The seal case 216 includes acavity 234 formed therein within which the stator 218 is disposed. Thestator 218 is configured to sealingly engage with the rotor sealing face222, and in this regard, includes a sealing face 236. Preferably, aspring 238 is included that has a preload suitable for applyingsufficient force against the stator 218 to thereby bias the statorsealing face 236 to sealingly contact the rotor sealing face 222. Thestator 218 may be further secured within the seal case 216 by aretaining ring 240 and an O-ring 242.

During operation, the spacer ring 202 and the rotor 214 are engaged withone another via the spacer grooves 210, 212 and rotor flanges 224, 226and both rotate with the shaft 104 with minimal axial travel along theshaft 104. The spring 238 applies force against the stator 218 so thatthe stator sealing face 236 and rotor sealing face 222 engage oneanother to thereby seal the opening 114.

There has now been provided a seal assembly that is effective even whena hydraulic pump stator and a rotor experience axial traveltherebetween. In addition, the seal assembly continues to beoperational, in the event metal chips are generated inside the pump.

While the invention has been described with reference to a preferredembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt to a particularsituation or material to the teachings of the invention withoutdeparting from the essential scope thereof. Therefore, it is intendedthat the invention not be limited to the particular embodiment disclosedas the best mode contemplated for carrying out this invention, but thatthe invention will include all embodiments falling within the scope ofthe appended claims.

1. A seal assembly for a hydraulic pump, the assembly comprising: aspacer ring; a rotor having a first side and a second side, the firstside engaging the spacer ring; and a spring-loaded face seal having aface in contact with the rotor second side, the face seal configured tosupply a force against the rotor sufficient to cause the face seal faceto sealingly engage the rotor second side.
 2. The seal assembly of claim1, wherein the rotor has an inner surface and the assembly furthercomprises an O-ring contacting the rotor inner surface.
 3. The sealassembly of claim 1, wherein the spacer ring has an end, and theassembly further comprises: a groove formed in the spacer ring end; anda flange formed on the rotor first side, the flange disposed within thegroove.
 4. The seal assembly of claim 1, wherein the spacer ring has anend and the assembly further comprises: a groove formed in the rotorfirst side; and a flange formed on the spacer ring end and disposedwithin the groove.
 5. The seal assembly of claim 1, wherein the spacerring has an end, and the assembly further comprises: a first and asecond groove each formed in the spacer ring end; and a first and asecond flange each formed in the rotor first side and each disposedwithin the first and second grooves, respectively.
 6. The seal assemblyof claim 1, wherein the face seal comprises: a seal case; a statordisposed within the seal case, the stator having the face; and a springdisposed within the seal case, the spring configured to supply the forceagainst the rotor to cause the face seal face to sealingly engage therotor second side.
 7. The seal assembly of claim 1, further comprising abearing assembly coupled to the spacer ring.
 8. The seal assembly ofclaim 1, further comprising a shaft to which the spacer ring and rotorare mounted.
 9. The seal assembly of claim 8, wherein the shaft isconfigured to be coupled to a gearbox.
 10. A hydraulic pump, comprising:a housing; a shaft rotationally mounted at least partially within thehousing; a spacer ring mounted to the shaft; a rotor mounted to theshaft and having a first side and a second side, the rotor first sideengaging the spacer ring; and a spring-loaded face seal coupled to thehousing and having a face in contact with the rotor second side, theface seal configured to supply a force against the rotor sufficient tocause the face seal face to sealingly engage the rotor second side. 11.The pump of claim 10, further comprising: an O-ring disposed between therotor and the shaft.
 12. The pump of claim 10, wherein the spacer ringhas an end, and the pump further comprises: a groove formed in thespacer ring end; and a flange formed on the rotor first side, the flangedisposed within the groove.
 13. The pump of claim 10, wherein the spacerring has an end and the pump further comprises: a groove formed in therotor first side; and a flange formed on the spacer ring end anddisposed within the groove.
 14. The pump of claim 10, wherein the spacerring has an end, and the pump further comprises: a first and a secondgroove each formed in the spacer ring end; and a first and a secondflange each formed on the rotor first side and each disposed within thefirst and second grooves, respectively.
 15. The pump of claim 10,wherein the face seal comprises: a seal case; a stator disposed withinthe seal case, the stator having the face; and a spring disposed withinthe seal case, the spring is configured to supply the force against therotor to cause the face seal face to sealingly engage the rotor secondside.
 16. The pump of claim 10, further comprising a bearing assemblydisposed concentrically around the shaft, wherein the spacer ring isdisposed between the bearing assembly and the shaft.
 17. The pump ofclaim 10, wherein the shaft is configured to couple to a gearbox.
 18. Aseal assembly for a hydraulic pump, the system comprising: a spacerring; a rotor having a first side and a second side, the first sideengaging the spacer ring; a stator having a face in contact with therotor second side; a seal case within which the stator is disposed; anda spring disposed within the seal case, the spring configured to supplya force against the rotor that is sufficient to cause the stator face tosealingly engage the rotor second side.
 19. The seal assembly of claim18, wherein the spacer ring has an end, and the assembly furthercomprises: a groove formed in the spacer ring end; and a flange formedon the rotor first side, the flange disposed within the groove.
 20. Theseal assembly of claim 18, wherein the spacer ring has an end and theassembly further comprises: a groove formed in the rotor first side; anda flange formed on the spacer ring end and disposed within the groove.